Ample flexibility of plant operation due to varying submergence.
Simple but robust mechanical equipment.
Practically no operator attention.
Reduced forces on gear unit.
Very high oxygen transfer efficiency, 2.2 to 3 kg/kwh.
Oxygen transfer not affected by age of aeration unit.
Low recurring and maintenance cost.
Low capital cost.
Material of construction :
SS 304 / 316
FRP (Fiber reinforced plastic ).
MS FRP lined
Flexibility of mounting:
Can be mounted on fixed platform
Floating aerator are mounted on three floats made from FRP
loating type is often used in rectangular and round tanks and lagoons, especially when water level is subjected to frequent variation.
Depth of aeration tank is no criteria:
or deeper tanks, updraft tube can be positioned below the aerating cone and terminates in the form of a bell mouth few inches above the bottom of the tank.
Three or four tie rods with adjustable turn buckle secures the upper end of the tubes to the walls of aeration tank.
The up draft tube is constructed from steel plate and the tubes examined after 10 to 15 years of operation without any protective treatment after initial installation have shown no deterioration in thickness; the waste water itself acts as the most effective corrosion inhibitor.
Control of Oxygen input :
Function of the intensity of aeration.
More the aeration more is the Oxygen input and vice versa.
Three methods of controlling the intensity of aeration :
By height adjustable aerator equipment − the submergence of aerators can be adjusted by 75 mm on either side of the mean water level in the aeration tank
By varying the number of revolutions per minute− the aerator can be fitted with a dual speed motor or VFD.
By varying the water level in the tank − the water level can be adjusted in the tank by means of an adjustable overflow weir.
Aeration tanks, rectangular, square, or round.
Activated sludge plants.
Extended aeration plants.
Sequencing batch reactors.
Latest Trends :
Use of helical geared motors even for higher power rating, planetory gearboxes and Cyclo gear boxes as drive units for aerators.
SS/FRP material for aerator impellers.
PLC control of outlet weir gates by sensing the DO level in the aeration tank with DO meter.
Direct Drive Aerator
Low capital cost.
Practically no maintenance.
Needs no painting as it is made of FRP.
Takes shock loads.
Depth of lagoon is no criteria as it can be adapted to any depth by using draft tube.
Can impart oxygen at 1.4 kg/kwh under standard conditions.